Technical Field
The technical field generally relates to camera calibration and distance determination, and more particularly, in one aspect, to systems and methods for calculating user distance from an object during an eye examination.
Background Discussion
Eye examinations are routinely used to determine the appropriate lens prescription for patients. One variable that must be known to perform an effective eye exam is the distance between a test subject and the displayed eye test. Eye exams have traditionally been performed by optometrists or the like in an office where a set distance from the patient to an eye chart or other testing material is easily maintained. Efforts to translate eye exam procedures from a doctor or technician's office to non-traditional locations such as self-administered tests at home are hampered by the difficulties associated with a user's ability to determine with confidence his or her distance from the testing material so that reliable results may be obtained. Proposed solutions such as using measuring tape or counting steps to determine a distance from a computer screen displaying an eye test require additional equipment or steps and may erode a user's confidence in the results, making a test administered out of office less attractive.